The traditional method of making sweet pickles is a process known as a tank sweetening. In the tank sweetening method, pickle stock is sweetened by immersion in a series of progressively more concentrated sugar solutions until the concentration of the sugar solids in the pickle is raised to about 40.degree. Brix (22.degree. Baume, 40% by weight). In a typical process, pickle stock is first placed in a tank containing a syrup that is 30% sugar by weight. After one day, diffusion has caused the sugar concentration to equalize in the liquid phase and the pickle at about 15% by weight. The liquid phase is then either replaced with a higher concentration syrup or withdrawn, mixed with additional solid sugar to raise the concentration, and then returned to the tank. By a series of such step-by-step increases in sugar concentration, the desired 40.degree. Brix sweet pickles can be produced in a period of about 3 to 15 days.
Tank sweetening on a commercial scale has several disadvantages. First, the multi-step increases in sugar concentration requires that a manufacturer employ multiple tanks. Furthermore, the process produces large quantities of excess syrup. Finally, tank sweetening is undesirable because of the numerous sanitary and safety hazards associated with handling the syrup (e.g., contamination and spillage).
It would be extremely desirable if sweet pickles could be produced by a one-step immersion in a syrup, particularly if the syrup and pickles could be combined directly in a retail container, such as a glass jar or other package. Placing whole pickles in highly concentrated syrups, however, would be expected to significantly shrink the pickle stock irreversibly due to the extremely high osmotic pressure between the concentrated sugar syrup and the high water content of the pickle stock. The water content of cucumbers, for example, is above 90% by weight. Water migrates from the pickle stock into the surrounding liquid phase much more rapidly than the sugar can migrate across the membrane of the cucumber. The net effect is that the pickle stock shrinks substantially and irreversibly.
A method of producing a moderately sweet pickle in a single immersion step has been developed. In this method, the pickle stock is first pricked with a commercial pricking panel and then immersed in a mixture of corn syrup and vinegar containing about 60% corn syrup solids by weight. The resulting pickle has a sweetener content of only about 30.degree. Brix (30% by weight) or less and is not, therefore, desirable to many consumers. Furthermore, even with the pricking, the pickles begin to show shrinking at a 60% corn syrup solids concentrations. This one-step method, although advantageously simplified, does not produce the sweet pickle with a 40.degree. Brix sweetener concentration as desired by many consumers.
Commercial scale production of pickles generally employs liquid sweetener solutions, such as dissolved sucrose or corn syrup. The maximum concentrations of solids in sucrose solutions is generally about 66% by weight. Higher concentrations can solidify under handling or processing conditions and an enormous effort is required to remove the solidified sugar from containers or equipment. Commercial scale production methods, therefore, are generally limited to solutions of no more than 66% sucrose by weight.
Thus, it is readily apparent that it be desirable to the art to develop a method of producing sweet pickles that reduces process steps, yet still produces a sweet pickle with a sweetener content greater than 30.degree. Brix, and also reduces the danger of high-concentration sucrose solutions solidifying during processing or handling.